- 18 Oct 2020
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Nearly 138 possible vaccine variations are under development all over the world. The science of vaccines have always remained a tricky tale to tell. Three out of the lot are reported to have reached human testing stage.
As good and cheesy the above statement be pleasing to hear, the truth however is that a vaccine is unlikely to be in mass public use till mid-2021. On an average, a vaccine takes 5 to 6 years for development, some as much as 10 years before a perfect vaccine is there for harmless use. To understand the same we have to first understand the science behind the vaccination.
● What is the basic science behind Vaccines?
Vaccine is a form of pathogenic residue or a pathogen form active or inactive given to the body for enhancing the immunity generation of antibodies against that particular pathogen. Whenever a known, unknown pathogen enters the body, the B cells a type of white blood cells produces Ig (immunoglobulin) antibodies and spreads them in blood circulation everywhere in the body. Once the pathogen’s location is identified, the immune cells sends killer T cells and neutrophils to neutralise the infected cells. The key factor is always how early the body detects the infection. The earlier, the better are the hopes of revival. So, it becomes very important to keep your immunity strong and healthier. A King who keeps his fort weak is defeated easily, no matter how bravely he can fight the enemy.
Every child before birth, gets IgG antibodies from their mother’s womb in the 6th month of pregnancy. It protects the child from outside infections but is short lived. Hence, a dose of mother’s milk which has IgM antibodies becomes compulsory for any child to remain healthy after birth. A King who has the required weaponry in his armoury is always considered a powerful king.
Now if body is attacked by a pathogen once, the soldiers in the armoury take out few selected weapons called immune cells, which are guarded by a messenger called cytokines. They go all out against enemy and defeat the pathogen. So, if a known enemy or pathogen attacks the body again, the armoury already knows which weapon to use, they eliminate the enemy in seconds. That is why those who are affected once by diseases like Chickenpox etc are not affected again.
● What is virus Mutation?
Now, it is never advised to introduce deadly virus in your body, it may kill the patient. Hence an attenuated form, or an inactive form is introduced, the point of weakness being the same as that of live virus. Sometimes, a portion of the pathogen like proteins, lipids, sugar etc. are introduced that are extracted from the virus except the RNA, which is the real deadly portion of the virus.
Chickenpox vaccine is made from live but a weakened form of virus, while Polio vaccine uses an inactive pathogen. The basic code of every virus are encrypted in the RNA portion which on entering the cell acts like a Xerox machine, which makes several copies of itself.
“Now, a faulty xerox machine may print few pages darker while few copies lighter and few as it is. This discrepancy in copying itself is called mutation, where sometime the virus changes its structure or sometimes develops extra strains and become more deadly. Best example of highly mutating virus is the human Influenza virus or the Flu virus. It can mutate severely. It has close to 14000 different nucleotides. An average person has over 200 Flus in one’s lifetime. 28 alphabets of genetic code keep evolving every year.”
Now, since Flu virus mutates very differently and mutated version have nothing in common with each other. But another virus called measles virus has a specific characteristic. Even though having 15,894 nucleotides, it has just 23 alphabets alphabets of genetic code till now. The common part is the haemagglutinin protein. Hence, a vaccine has been possible which incites the antibody to react to the haemagglutinin protein. No matter the number of strains evolved this common factor becomes the last dying wish for the virus.
● How the novel Coronavirus or COVID-19 virus fare in vaccinology?
Just like every other virus out there, genome of SARS COV-2 is mutating continuously. Till now scientists have found 12 mutations in the virus suggesting that it is mutating every 15 days. Now the art is to identify that one common property in the virus among various mutations.
The virus attacks the ACE2 receptors of respiratory system. Read here to understand how the virus attacks and affects the body. So, all the vaccines will fare around this receptor. Any sort of change in spike protein and virus will not be able to enter inside the human cell. In simple terms if the virus mutates and changes spike protein, such a mutation will be good news for humanity. So, the focus remains on developing antibodies for the spike protein of novel coronavirus. Entire vaccine research will revolve around this commonality.
There are different ways to go at this virus.
One way is to inject a weakened form of virus, by making the patient ingest it live like a pill. This will generate some symptoms of the virus like mild fever etc. but will generate an immune response in the body. Until such a method is tried and tested on a large sample space it will not be used. So, this methodology needs time but will give life long immunity to all patients.
Another way is to have the spike protein genome assimilated into a harmless virus and same be administered via a nasal path like the infections usually take place. The immune system thus will generate antibodies for the spike protein and be an effective vaccine against the virus.
New developments across the world that gives us hope:-
● Indian scientists have sequenced 185 samples so far. They are on a quest to isolate 100 different samples for a good comparative study. The Centre for Cellular and Molecular Biology (CCMB) and Institute of Genomics and Integrative Biology (IGIB), Council of Scientific and Industrial Research’s (CSIR), are together undertaking this what may seem a herculean task, but researchers are confident of doing it on war footing.
● Indian Council of Medical Research (ICMR) and Bharat Biotech International Limited (BBIL) are together developing COVID-19 vaccine, which use strain from National Institute of Virology (NIV), in Pune.
● World’s largest producer of vaccines, Serum Institute of India (SII), in partnership with Oxford University has teamed up to mass produce 60 million doses of COVID-19 vaccine.
● Vaccine candidate ‘ChAdOx1 nCoV-19’ is developed by The University of Oxford. The research is using an attenuated strain of adenovirus, the usual common cold virus mixed with spike protein of novel coronavirus.
● US based Moderna Therapeutics and Novavax are now moving towards second phase of humans trials.
● British American Tobacco has claimed that their tobacco enhanced antigen which after injection into tobacco plants will act as a natural vaccine candidate.
● French Pharmaceuticals Sanofi’s is using a vaccine, previously used for influenza and being applied to the Covid-19 virus.
● The Ad5-nCoV vaccine developed by the Chinese Pharma Cansino Biologics, is the first to enter the second phase of human clinical trials. It is another spike protein-based version of the Flu Virus.
● Tel Aviv University in Israel is developing a safer form of virus which is based on a more focussed approach. It will target an identified weaker part of virus and not the entire spike protein structure.
The world is taking giant leaps in developing a COVID-19 vaccine candidate. Which one of these will be successful in all the trials, only time will tell. But even though all of them are successful, it is not a far-off truth to understand that it will still take a year or two from now to be ready for public use. Till then hope is on what the world rests.